Stacker door upgrades in Berwick.
Every new-estate house from Edenrise to Clyde North got the same 2.4m two-panel builder slider, and it is the single most common thing owners want gone. Widening that opening to a 3.6m stacker is the best-value change you can make to a Berwick living room. It is also a structural job, not a window swap. Here is what it really involves.
What actually happens when you widen the opening.
There are two versions of this job and they are wildly different in scope. If your house already has a wide opening, say a 3.6m aperture with a tired old three-panel slider in it, then swapping it for a stacker is a like-for-like replacement in an existing opening. Permit-exempt, one day, $4,500 to $6,500. That is the easy version and it is not what most people are asking about.
The common version is widening a standard 2.4m builder slider to 3.6m or 4.2m, and that is a structural alteration. You are taking out a chunk of load-bearing wall and putting a longer lintel back in: on a Berwick brick veneer, a steel lintel carrying the brick skin and a member carrying the roof load from the frame above, propped through the work, sized by an engineer to AS 1170. Casey estate lots are generally wind classification N2 under AS 4055, with N3 on the exposed foothill blocks around Harkaway and Narre Warren North, and that classification feeds the design.
The sequence, honestly.
- Engineer's lintel design. $600 to $1,200. Nobody sizes a 3.6m lintel by eye, and no surveyor will issue a permit without it.
- Building permit from a private building surveyor. $700 to $1,800, two to three weeks, with mandatory inspections. This is not optional and it is covered in full on our Casey permits page.
- Propping and demolition. The roof load has to be carried while the old lintel comes out. This is the part that makes it a builder's job.
- New lintel in, brickwork made good. $900 to $2,000 depending on how well the new brick can be matched, and on a 2003 house it usually cannot be matched exactly.
- Stacker in, threshold waterproofed, perimeter sealed. The part everyone thinks is the whole job.
- Internal make-good and paint. Plaster, architrave, cornice, then the painter, two days later once the sealant has cured.
Manufacture lead time is four to six weeks and runs in parallel with the permit, so it rarely adds to the calendar. The best time to do this work in Casey is autumn, for the reasons set out on our seasonal timing page, and there is a specific reason here: this job opens a large hole in your living room wall for the better part of a day.
Where stacker doors leak, and why.
If we get called back to a stacker two winters after someone else installed it, it is the threshold. Not the door, not the glass, not the rollers. The threshold, and specifically the fact that the deck or the paving outside it finished up too high.
The raised threshold is the safe detail. The track sits on an upstand, water outside physically cannot get over it, and the door will still be dry in twenty years. It is also a trip edge and it interrupts the seamless indoor-outdoor look people are paying for.
The flush threshold is what everyone wants, and it is genuinely achievable, but only when the drainage is designed in from the start: a grated channel drain running the full width immediately outside the track and connected to stormwater, the finished deck or paving set below the track with a fall away from the house, and someone thinking about it before the deck is built rather than after. Flush threshold, plus a deck built dead level with the internal floor, plus no channel drain, equals water in your living room on the first serious Casey downpour.
This is why we ask about your deck before we quote a stacker, and why the order of trades matters: door first, deck second, so the deck builder sets their height off the finished track instead of us guessing at theirs. Our local trades page covers how that sequencing works across Casey.
Weight, glass and hardware.
A double-glazed stacker panel runs roughly 80 to 120kg. That number drives three decisions. The head has to be dead straight, because a lintel that sags even slightly over 3.6m will bind the panels inside a year. The track has to be set with no twist, because a millimetre of rack over that span stops the door sealing. And the rollers are not the place to economise: put cheap rollers under 120kg of glass on Casey's reactive clay, which is typically H1 or H2 under AS 2870 and moves the whole house seasonally, and in five years the door slides like a wardrobe. Glass is Grade A toughened per AS 1288, non-negotiable in a doorway, and the completed unit carries its AS 2047 label for wind load, water penetration and operating force.
A worked example, and whether a bifold is the better answer.
Worked example, 2026. Single-storey brick veneer in Berwick, built 2016, standard 2.4m two-panel aluminium slider from the family room onto a paved alfresco. Owner wants a 3.6m three-panel double-glazed stacker. Engineer's lintel design $850. Building permit through a private surveyor $1,150. Propping, demolition, new steel lintel and brickwork make-good $1,700. Stacker supply and install, 3.6m, double-glazed, Monument powder coat, $5,800. Internal plaster and architrave make-good $700. Channel drain and re-set the first course of paving to get a flush threshold $1,400. Total $11,600, plus the painter. Elapsed time about seven weeks, of which five is the permit and the manufacture running side by side, and three days on site.
Against that, the same owner could keep the 2.4m opening and just put a better double-glazed slider in it for about $2,600, no permit, one day. That is a legitimate choice and we quote it every time. The $9,000 difference buys 1.2m of extra opening and a room that connects to the yard, which is either the whole point or a waste of money depending on how you live. We are not going to pretend it is an investment: nobody has ever recouped a stacker on a valuation.
Stacker or bifold? A stacker slides its panels behind each other at one end and gives you about two thirds of the opening clear. A bifold folds against the jamb and gives you close to the whole opening, at $5,500 to $9,500 for three panels against $4,500 to $6,500 for a comparable stacker. The lintel, permit and threshold work is identical either way, so the decision is about the door, not the build. Our honest bias for Casey family homes is the stacker, for one unglamorous reason: you can crack a single panel for a breeze without unfolding the whole wall, and that is what you do 360 days a year. The bifold wins the other five days, and it wins them convincingly. Both are on our bifold doors page and our sliding doors page, and the full per-opening bands are in the Berwick pricing guide.
Stacker upgrade questions we get asked.
What does it cost to upgrade a standard sliding door to a stacker in Berwick?
If the opening stays the same size, a 3.6m stacker into an existing wide opening runs about $4,500 to $6,500 installed in 2026. If the opening has to be widened, which is the usual case when going from a standard 2.4m builder slider, add an engineered lintel at roughly $1,200 to $2,800, a building permit at $700 to $1,800, brickwork and reveal make-good at $900 to $2,000, and an engineer's design fee of $600 to $1,200. The realistic all-in for widening a 2.4m opening to a 3.6m stacker on a Berwick brick veneer is $8,500 to $13,500.
Do I need a permit to widen a doorway for a stacker in Casey?
Yes. Replacing a door in the same opening is permit-exempt like-for-like work under Schedule 3 of the Building Regulations. Widening the opening is not, because you are removing part of a wall and installing a new lintel, which is structural. You need an engineer's lintel design and a building permit from a private building surveyor, and the surveyor inspects at the mandatory stages. Two to three weeks is typical for the permit. Anyone offering to widen the opening without one is offering you an illegal structural alteration on your own title.
What is the difference between a stacker and a bifold?
A stacker slides panels sideways so they park behind each other at one end, typically giving you about two thirds of the opening clear. A bifold folds concertina-style against the jamb and gives you nearly the whole opening clear, which is the better result if the view and the flow matter most. The trade-offs are cost and daily use. A three-panel bifold runs $5,500 to $9,500 against $4,500 to $6,500 for a comparable stacker, and a stacker lets you crack one panel open for a breeze without unfolding the whole wall.
Why do stacker doors leak, and how is it prevented?
Almost always the threshold, and almost always because the deck or paving outside finished up too high. Water needs somewhere to go and a fall away from the door to take it there. A standard raised threshold is the safe detail because it puts a physical upstand between outside water and your floor. A flush threshold looks better and is genuinely achievable, but it is only safe when the drainage is designed in: a grated channel drain immediately outside, correct falls, and the finished deck or paving set below the track. Flush threshold plus a deck built level with the floor plus no drain equals water inside, every time.
How heavy are stacker door panels and does that matter?
A double-glazed stacker panel runs roughly 80 to 120kg, which matters in three ways. It is why the head has to be dead straight, because a sagging lintel over a 3.6m opening will bind the panels within a year. It is why the track has to be set with no twist, since a millimetre of rack over that span is enough to stop the door sealing. And it is why the roller specification is not a place to save money: cheap rollers under 120kg of glass on Casey's reactive clay, which moves the whole house seasonally, are the most common reason a five-year-old stacker feels like a wardrobe door.
Stacker and slider upgrades across Casey.
Thinking about widening that builder slider?
Free measure. We price the like-for-like swap and the full stacker widening side by side, permit and lintel included.